Help to ID this lamp base?

[Tim]

I came across an unusual bulb ? unusual mainly because I can?t identify the base type.  This is a GE Mazda railroad signal lamp, probably from the 1940s, and commissioned by the Union Switch & Signal Company.  The lamp is fitted with a precision base made of two separate pieces soldered together with a single contact button on the bottom.  The base diameter measures 23.75mm and has two opposing tabs (not pins) as shown in the photos.  Does anyone know the correct industry nomenclature for this particular lamp base?  I can?t find anything similar in my catalogs.

[Nick D.]

Tim, that reminds me of the World's Fair scandal where GE was jabbing at Westinghouse after Edison lost the electrical contract for the fair. One of the things Westinghouse did (besides coming up with a bulb) was develop a slip-cover of sorts that could convert Westinghouse's single-pin stopper lamp into an Edison screw base. What I think happened to your bulb (though not very likely) was that someone soldered part of a different base onto an Edison(?) one.

Just a lame idea...

[Tim]

Hi Nick,

Thanks for the feedback regarding the base.  I agree that a sleeve has been soldered on but I have to believe this was done at the lamp factory (or perhaps by US&S Co.) because of the quality of the solder joints.  I have seen at least three other similar bulbs with the same two-piece constructed base.  I?ve also found the bulb and this base illustrated in some old US&S Co. literature (see attachment below).  In this literature, they refer to the base as a ?special rebased base? ? not sure exactly what this means though.  I don?t think there are Edison threads underneath the outer sleeve, but rather this seems like some type of modified precision pre-focus base.